The stepfather of Amanda Knox, jailed for the murder of British student Meredith Kercher, has said he would not return home until the American student was released from jail.

The 23-year-old, dubbed Foxy Knoxy, is appealing against her conviction and 26-year prison sentence for killing her housemate in the Italian hilltop town of Perugia.

But her relatives are now hopeful the end to her detention is in sight after independent forensic experts were granted 90 days to re-examine crucial evidence used against her. However, the lengthy review means Knox has months to wait before she learns her fate.

University of Leeds student Miss Kercher, 21, from Coulsdon, Surrey, was found with her throat slit on November 2 2007, in her bedroom at the house she shared with Knox and others during her year abroad. Her semi-naked body was partially covered by a duvet.

Knox, from Seattle, and her former lover Raffaele Sollecito, 26, were later charged with sexual assault and murder following what prosecutors claimed was a sex game taken to the extreme. They were handed prison sentences of 26 years and 25 years respectively last December.

Though Knox is now increasingly concerned for her future, her stepfather Chris Mellas insisted the developments were "definitely a step in the right direction".

Mr Mellas, who moved to Italy in September to support his stepdaughter and was in court along with her school friend Madison Paxton, added: "I have been over here for much too long already but I will stay here for as long as it takes. The day that she goes home is the day that I move home."

Dressed in a simple white top and black jacket, Knox offered only a few smiles to her legal team in court, listening intently as experts Stefano Conti and Carla Vecchiotti from Rome's Sapienza University were formally sworn in ahead of their review.

The pair will consider disputed DNA traces found on a kitchen knife - the alleged murder weapon - and on the clasp of Miss Kercher's bra. Though used to secure her conviction, Knox's lawyers argue this evidence was inconclusive and may have been contaminated when analysed.

Experts appointed by both the prosecution and the defence will be present at the examination which is expected to be completed by May 9, and they will report their findings to the court on May 21.